Multiple-input-multiple-output (MIMO) wireless communication has the potential to significantly increase communication system capacity without requiring increases in transmitting power or spectrum. If M transmit and M receive antennas are used in a Rayleigh flat-fading communication environment, a theoretical linear M scale increase in channel capacity can be achieved. One challenge of MIMO wireless communication systems is the construction of compact MIMO antennas in order to be incorporated within the shrinking dimensions of communication devices.
Although a number of compact MIMO antennas consisting of up to 4 ports (including designs based on planar inverted F antennas (PIFAs) and patch antennas) have been proposed, compact antenna designs with more than 10 ports are less common and mainly consist of a flat panel approach used in base-stations. Additionally, although MIMO antennas have been developed using a cube configuration, such antennas have used up to 12 electrical dipole antennas on its 12 edges.
One advantage of a MIMO cube configuration is that, in a rich scattering environment, the MIMO cube takes advantage of spatial and polarization diversities in a compact volume. Although further increases in the number of antennas on a cube can further increase the theoretical channel capacity, it can also produce high mutual coupling between individual antennas, leading to increasing correlation and decreasing capacity.
The above-described deficiencies are merely intended to provide an overview of some of the problems encountered in implementing high capacity compact antennas, and are not intended to be exhaustive. Other problems with the state of the art may become further apparent upon review of the description of the various non-limiting embodiments of the disclosed subject matter that follows.